Abstract No. 371: Percutaneous CT-Guided Conformal Ultrasonic Ablation of Vertebral Tumors Using a Rabbit Tumor Model

Article Outline

• Purpose
• Materials and Methods
• Results
• Conclusion
• Copyright

Back to Article Outline

Purpose 

Radiofrequency ablation (RFA) has proven effective for treatment of malignant and benign tumors outside the spine. The major challenge of using RFA for spinal tumors is difficulty protecting the cord and nerves from RFA damage. However, conforming ultrasound energy to match the anatomy of the tumor may provide successful ablation in such ocations. Using a rabbit model of vertebral body tumor, we have successfully treated tumors using an acoustic ablator placed percutaneously via computed tomography fluoroscopic (CTF) guidance.

Back to Article Outline

Materials and Methods 

Using CTF guidance, adult New Zealand white rabbits were injected with VX2 carcinoma cells in the lowest lumbar vertebral body. At 21 days, a bone biopsy needle was placed into the center of the lesion, down which an acoustic ablator was inserted. Thermocouplers were placed around the lesion to provide measurement of tissue temperature, and tumor volumes were given a tumoricidal dose of acoustic energy. Animals were monitored for 24 hours and sacrificed. Histology was obtained to determine extent of tumor death and surrounding tissue damage. Thermocoupler data were used to reconstuct volumetric doses of energy delivered to tissue, and such data were correlated with pathological findings.

Back to Article Outline

Results 

Rabbits were successfully implanted with VX2 cells, leading to a grossly apparently spinal and paraspinal tissue mass. CTF guidance provided accurate placement of the acoustic ablator, as corroborated via gross and microscopic histology. Significant tumor kill was noted in all specimens without collateral damage to nearby nervous tissue. Marginal kill was noted in some, but not all specimens. Reconstruction of thermocoupler data allowed accurate assessment of volumetric dose delivered to tissues.

Back to Article Outline

Conclusion 

Using a rabbit intravertebral tumor model we have successfully delivered tumoricidal doses of acoustic energy via a radiofrequency ablation probe placed percutaneously via CT-fluoroscopy guidance. We have thus established the technical and pre-clinical feasibility of controlled ultrasound ablation of spine tumors in vivo.